View source for EMD F-unit

{{Short description|Line of diesel-electric locomotives}}
{{More footnotes needed|date=August 2013}}
[[File:ATSF 21L F3A with Train -2, the San Francisco Chief between Willow Springs, IL and Lemont, IL on the only stretch of ATSF track in DuPage County on January 2, 1967 (22692932325).jpg|300px|thumb|[[Atchison, Topeka and Santa Fe Railway|AT&SF]] {{abbr|No.|Number}}&nbsp;21, an EMD F3, leading the ''[[San Francisco Chief]]'' in Illinois in 1967]]
'''EMD F-units''' are a line of [[diesel-electric locomotive]]s produced between November 1939 and November 1960 by [[General Motors Corporation|General Motors]] [[Electro-Motive Diesel|Electro-Motive Division]] and General Motors-Diesel Division. Final assembly for all F-units was at the GM-EMD plant at [[La Grange, Illinois]], and the GMDD plant in [[London, Ontario]]. They were sold to [[railroad]]s throughout the [[United States]], [[Canada]] and [[Mexico]], and a few were exported to [[Saudi Arabia]]. The term ''F-unit'' refers to the model numbers given to each successive type (i.e. F3, F7, etc.), all of which began with the letter ''F''. The ''F'' originally meant "fourteen", as in {{convert|1400|hp}}, not "freight". Longer [[EMD E-units]] for passenger service had twin {{convert|900|hp|adj=on}} diesel engines (called "[[Prime mover (locomotive)|prime movers]]" in that type of application). The ''E'' meant "eighteen" as in {{convert|1800|hp}}. Similarly, for early model EMD switchers, ''S'' meant "six hundred" and ''N'' meant "nine hundred horsepower" ({{cvt|600|and|900|hp|disp=out}} respectively).{{citation needed|date=February 2021}}
<!-- Image with inadequate rationale removed: [[Image:EMD FT demonstrator.jpg|thumb|250px|EMD's FT demonstrator set No.&nbsp;103, the locomotive that sold US railroads on the freight-hauling Diesel-electric locomotive.]] -->

F-units were originally designed for freight service, although many without [[Steam generator (railroad)|steam generators]] (for steam-heating passenger cars) pulled short-distance, mainly daytime, passenger trains. Some carriers even equipped small numbers of their Fs with steam generators for long-haul passenger service. On the other hand, [[Atchison, Topeka and Santa Fe Railway|Santa Fe]] maintained a large fleet of fully equipped, high-speed F3s and F7s in "warbonnet" paint schemes built exclusively for top-tier passenger trains, such as the ''[[Chief (train)|Chief]]'', ''[[Super Chief]]'', and ''[[El Capitan (train)|El Capitan]]''. Almost all F-units were [[AAR wheel arrangement#B-B|B-B]] locomotives, meaning that they ran on two [[Blomberg B]] two-axle [[bogie|trucks]] with all axles powered. The prime mover in F-units was a sixteen-cylinder [[EMD 567|EMD 567 series]] [[roots type supercharger|mechanically aspirated]] [[Two-stroke engine#Two-stroke diesel engine|two-stroke]] [[diesel engine]], progressing from model 16-567 through 16-567D.

Structurally, the locomotive was a [[carbody unit]], with the body as the main load-bearing structure, designed like a bridge [[truss]] and covered with cosmetic panels. The so-called [[bulldog nose]] was a distinguishing feature of the locomotive's appearance and made a lasting impression in the mind of the traveling public.

The F-units were the most successful "first generation" road (main line) diesel locomotives in North America and were largely responsible for superseding [[steam locomotive]]s in road freight service. Before that, diesel units were mostly built as [[switcher locomotive]]s and only used in rail yards.

F-units were sometimes known as "covered wagons",<ref>See, e. g., Young, William S. "Covered Wagons: The Early Road Diesels of the Erie Lackawanna" (1976, Starrucca Valley Publications).</ref> due to the similarity in appearance of the roof of an F-unit to the canvas roof of a [[Conestoga wagon]], an animal-drawn wagon used in the westward expansion of the United States during the late 18th and 19th centuries. When locomotives on a train included only F-units, the train would then be called a [[wagon train]]. Those two usages are still popular with the [[railfan]] community.

==Models==
{|class="wikitable sortable"
!Model designation!!Build year!!Total produced!![[AAR wheel arrangement]]!![[Prime mover (locomotive)|Prime mover]]!![[Horsepower|Power output]]!!class="unsortable"|Image
|- align="center"
|[[EMD FT|FT]] 
|1939–1945
|<span style="display:none">1096</span> 555 A units,<br/> 541 B units 
|[[AAR wheel arrangement#B-B|B-B]]<BR>([[AAR wheel arrangement#B-B+B-B|B-B+B-B]] with B unit) 
|[[EMD 567|EMD 16-567]]<BR>[[EMD 567|EMD 16-567A]] 
|{{convert|2700|hp|abbr=on}}<br/>(with B unit) 
|[[File:Santa Fe FT locomotive 1941.JPG|100px]]
|- align="center"
|[[EMD F2|F2]] 
|1946 
|<span style="display:none">0104</span> 74 A units,<br/> 30 B units
|[[AAR wheel arrangement#B-B|B-B]] 
|[[EMD 567|EMD 16-567B]] 
|1,350&nbsp;hp<br />(1,000&nbsp;kW)
|[[File:Joliet CRIP Aug 1963 3-16.jpg|100px]]
|- align="center"
|[[EMD F3|F3]] 
|1946–1949 
|<span style="display:none">1807</span> 1,111 A units,<br/> 696 B units 
|[[AAR wheel arrangement#B-B|B-B]] 
|[[EMD 567|EMD 16-567B]] 
|1,500&nbsp;hp<br />(1,100&nbsp;kW) 
|[[File:BN 9762 in Yakima Aug 71 NthCstHiRP.jpg|100px]]
|- align="center"
|[[EMD F7|F7]] 
|1949–1953
|<span style="display:none">3849</span> 2,366 A units,<br/>1,483 B units 
|[[AAR wheel arrangement#B-B|B-B]] 
|[[EMD 567|EMD 16-567B]] 
|1,500&nbsp;hp<br />(1,100&nbsp;kW) 
|[[File:ATSF 309 (Flickr 22322834666).jpg|100px]]
|- align="center"
|[[EMD FP7|FP7]]
||1949–1953
||<span style="display:none">0090</span> 381 [[A unit]]s,<br/>no [[B unit]]s
||[[AAR wheel arrangement#B-B|B-B]]
||[[EMD 567]]B
||1,500 [[Horsepower|hp]]<br />(1,200 [[Watt#Kilowatt|kW]])
|| [[File:WP 805A and train 2 Sparks NV 2004 WPRRHS Convention e.jpg|100px|Western Pacific 805-A, an FP7 preserved at the Western Pacific Railroad Museum in California]]
|- align="center"
|[[EMD F9|F9]] 
|1953–1960 
|<span style="display:none">0255</span> 99 A units,<br/>156 B units 
|[[AAR wheel arrangement#B-B|B-B]] 
|[[EMD 567|EMD 16-567C]] 
|1,750&nbsp;hp<br />(1,200&nbsp;kW)
|[[File:Crm california zephyr.jpg|100px]]
|- align="center"
|[[EMD FP9|FP9]]
||1954–1959
||<span style="display:none">0090</span> 90 [[A unit]]s,<br/>no [[B unit]]s
||[[AAR wheel arrangement#B-B|B-B]]
||[[EMD 567]]C
||1,750 [[Horsepower|hp]]<br />(1,300 [[Watt#Kilowatt|kW]])
|[[File:FP9Au RLGN 1400.jpg|100px|RLGN 1400 at Waterloo, Ontario, October 7, 2003]]
|- align="center"
|[[EMD FL9|FL9]]
||1956–1960
||<span style="display:none">0090</span> 60 [[A unit]]s,<br/>no [[B unit]]s
||[[AAR wheel arrangement#B-A1A|B-A1A]]
||[[EMD 567]]C or<br/>EMD 567D1;<br/> plus 660 V DC<BR>(3rd rail)
||567C:<br />1,750 [[Horsepower|hp]]<br />(1,300 [[Watt#Kilowatt|kW]]); <br/>567D1:<br />1,800 [[Horsepower|hp]]<br />(1,340 [[Watt#Kilowatt|kW]]) ||[[File:New Haven FL9 2010 near Enfield, July 1968.jpg|100px]] 
|}

== Model development ==
The [[EMD FT|FT]], introduced in 1939 with the new {{convert|1350|hp|MW|abbr=on|lk=in}} [[EMD 567|567]] engine and Blomberg B trucks, was a successful design, and remained in production during WWII.

The [[EMD F3|F3]] (1946) had a different roof arrangement that included the replacement of the FT's boxy dynamic brake structure with two under-roof grids, two exhaust stacks instead of four, and four cooling fans grouped together instead of separated pairs of cooling fans. The F3 was also {{convert|2|ft}} longer than the FT to allow a standard draft gear to be installed at the rear of the unit. The 567B engine was uprated to {{convert|1500|hp|MW|abbr=on}}. Some F3s were nicknamed "chickenwire" for the type of engine room air-intake structure along the sides.

The [[EMD F7|F7]] (1949) and [[EMD F9|F9]] (1954) were evolutionary: the F7 had improved traction motors, the F9 had a {{convert|1750|hp|MW|abbr=on}} 567C engine. A louver arrangement over the vents changed their appearance from the F3.

There were also {{convert|4|ft||adj=mid|-longer}} versions, the [[EMD FP7|FP7]] and [[EMD FP9|FP9]], the extra length being used to house a tank for extra water capacity. Only one F model did not have Blomberg B trucks: the [[EMD FL9|FL9]] [[electro-diesel]] locomotive had a lightweight Flexicoil B in front and a standard passenger A-1-A at the rear.

Model descriptions are as built, but EMC/EMD locomotives are often rebuilt to newer standards. 
<ref>{{cite book|last=Pinkpank|first=Jerry A|title=The Second Diesel Spotter's Guide|year=1973|publisher=Kalmbach Books|isbn=0-89024-026-4|pages=13, 26 90–95, 99–101}}</ref>
<ref name="ros03"/>

==Engine and powertrain==
The F series used a 16-cylinder version of the [[EMD 567|567]] series diesel engine, introduced in 1939. The 567 was designed specifically for railroad locomotives, a mechanically aspirated [[2-stroke|2 stroke]] 45 degree [[V engine|V type]] with {{convert|567|cuin|L|abbr=on}} displacement per cylinder, for a total of {{convert|9072|cuin|L|abbr=on}}. An ongoing engine improvement program saw the FT's original {{convert|1350|hp|abbr=on}} up-rated to {{convert|1800|hp|abbr=on}} in the FL9 by the end of F unit production. A DC generator powered four traction motors, two on each truck. The Blomberg B truck first used in the FT became the EMD production standard, being used until 1995. EMC/EMD built all of its major components after 1939.<ref name=ros03>{{cite book|editor-first=David|editor-last=Ross|title=The Encyclopedia of Trains and Locomotives|year=2003|isbn=978-0-7607-9679-5|pages=270–271, 295|publisher=Barnes & Noble }}</ref><ref>{{cite book|last=Pinkpank|first=Jerry A|title=The Second Diesel Spotter's Guide|year=1973|publisher=Kalmbach Books|isbn=0-89024-026-4|pages=13, 26}}</ref>

==Passenger service==
[[File:Amtrak San Francisco Zephyr.jpg|thumb|right|300px|[[Amtrak]] No.&nbsp;113, an [[EMD FP7]], leading two [[EMD SDP40F]]s with the ''[[San Francisco Zephyr]]'' at the Yuba Gap in 1975]]
While the F-unit series was originally conceived for freight service, many were used to haul [[passenger train]]s. The original EMC FT demonstrator was equipped with a [[Steam generator (railroad)|steam generator]] in the B units for train heating. Several railroads took advantage of the large space in the rear of their [[B unit]]s to add steam generators. The first FTs built strictly as a passenger unit was the Santa Fe 167 four unit set in February 1945. Learning from that, EMD offered an optional steam generator on all later F unit models. It was mounted at the rear of the car body; steam-generator equipped locomotives can be recognized by the exhaust stack and safety valves protruding at the rear of the roof.

The F-units were popular passenger locomotives on mountain grades (where they were recommended by EMD), because a four-unit set had more motored axles than a trio of [[EMD E unit|E-units]] of equivalent power (16 versus 12) and thus had less chance of overloading the traction motors. Additionally, the four F-unit set had all its weight on driven wheels and was thereby capable of greater [[tractive effort]]. The AT&SF ''[[Super Chief]]'', [[Chicago, Burlington and Quincy Railroad|CB&Q]]/[[Denver and Rio Grande Western Railroad|D&RGW]]/[[Western Pacific Railroad|WP]] ''[[California Zephyr]]'', and [[Great Northern Railway (U.S.)|GN]] ''[[Empire Builder]]'' all used F units on their Chicago-West Coast routes in the 1950s. The F7 was also popular for commuter lines and other passenger service where the trains were short.

==Options==
There were several options that could be specified by customers for the F-units, such as type and mounting location of [[train horn|horns]] and [[bell]]s.

===Dynamic brakes===
[[Dynamic brake]]s were an option on F units ordered by railroads operating in mountainous terrain and with steep grades.

===Passenger or freight pilot===
Either a passenger or freight style [[pilot (locomotive attachment)|pilot]] could be ordered. The passenger pilot, similar to that standard on E-units, slopes smoothly down from the bottom of the nose, making a single slope all the way down from the headlight. The coupler is retractable with concealing doors. The result is a very attractive appearance that enhanced the impression of a powerful and speedy machine.

The freight pilot curves inward a little way below the bottom of the nose before sloping out again, to give more clearance to the coupler and hoses. The coupler is fixed and protrudes through a rectangular opening in the pilot.

==See also==
* [[CF7]] - A rebuild of an EMD F unit by the [[Atchison, Topeka and Santa Fe Railway]].

==References==
{{reflist}}

== Further reading ==
{{refbegin}}
* {{cite book|author=Diesel Era|title=The Revolutionary Diesel: EMC's FT|year=1994|location=Halifax, PA, USA|publisher=Withers Publishing|isbn=1-881411-02-8}}
* {{Lamb-Evolution}}
* {{Marre-diesel-50}}
* {{Pinkepank diesel spotters guide 2}}
* {{Schafer-Vintage Diesel}}
* {{Solomon-American Diesel}}
* {{Solomon-EMD F-Unit}}
* {{Solomon-EMD Locomotives}}
* {{Solomon-Vintage Diesel}}
* {{Solomon-Electro-Motive}}
* {{Solomon-North American Locomotives}}
* {{Wilson-F Units}}
{{refend}}

== External links ==
* [https://www.railpage.com.au/locos/s-class Railpage - Australian implementation of the F7]
{{EMD cab and cowl}}

{{DEFAULTSORT:Emd F-Unit}}
[[Category:B-B locomotives]]
[[Category:Electro-Motive Division locomotives|F]]
[[Category:North American streamliner trains]]
[[Category:Diesel–electric locomotives of the United States]]
[[Category:Locomotives with cabless variants]]
[[Category:Standard-gauge locomotives of Canada]]
[[Category:Standard-gauge locomotives of the United States]]
[[Category:Standard-gauge locomotives of Mexico]]
[[Category:Standard-gauge locomotives of Saudi Arabia]]
[[Category:Diesel–electric locomotives of Canada]]
[[Category:Diesel–electric locomotives of Mexico]]
[[Category:Diesel–electric locomotives of Saudi Arabia]]